Method of cracking oils



Oct.V 5`,v 1937. D. M. EVANS 2,094,980

METHOD 0F CRACKING OILS Filed Oct. 28, 1955 FESH FEED E A cc MMI/A TakINVENTOR @Paf M EVA/v5 ATTORNEY ADQ/7704411. FIPA-'5H FEED Patented Oct.5, 1937 UNITED STATES 2,094,980 Y YMETHOD OF CRACKING OILS y Drue M.Evans, Wood River, Ill., assignor to Petroleum Conversion Corporation,New York, N. Y., a corporation of Delaware Application October 28, 1935,Serial No. 47,035

6 Claims. (Cl. 196-61) My present invention relates to a method ofcracking oils, preferably in the vapor phase, by the agency of hot gasconstituted in substantial part at least by the exhaust of aninternal'combustion engine. By suitably modifying the method ofoperating an internal combustion engine,

it is possible to produce a stream of gas having a temperature of 1100degrees F. or more and at a pressure say up to fifty pounds or morewhich I have found to afford a satisfactory medium for the cracking ofoil in the vapor phase. Preferably, tWo or more engines are used and theexhaust from these collected, a reservoir or surge chamber beingemployedif desired. The oil to be cracked is preferably vaporized and, ifdesired, the vapor produced is superheated, and the vapor which Visbelow the temperature of active cracking mingled with the hot gas andthe reaction allowed to proceed in a reaction chamber, the mixture ofproducts then progressively dephlegmated so, as to yield finally adesired product .of the cracking, as for example a distillate in thegasoline range, leaving a stream of gas which is more or less saturatedWith light vapors.

Desirably, the latter are recovered preferably by the use of an absorberwhereupon thefstripped gas Which comprises not only the combustion gasesoriginally present but the gas formedby the cracking of the oil or oilvapor, (the latter 30 varying in amount say from 8 to 15% of the oiladmitted to the system for cracking), is utilized as fuel for theinternal combustion engines, such mixture being of suicient fuel valuefor this purpose. When the fat oil from the absorber mentioned isheated, a gas is liberated of high thermal value and this preferably isadded to the gas fed to the internal combustion engines. The

superfluous gas which is not required as fuel in the engines is used invarious parts of the plant requiring heat, as for example for operatingthe Vaporizer for the oil to be cracked. The energy obtained by burningthe gas in the 'various' engines may be used for many purposes,including especially that of compressing the gases in the i system priorto their admission to the absorber.

' Some of the gas may also be heated by heat exchange with thedephlegmated products and the gas so heated added directly to thereaction chamber.

'3 The invention Will be best understood by reierence to the followingdetailed description taken With the annexed drawing in Which the gurerepresents diagrammatically a plant containing an V illustrativeembodiment of the invention. 'Ihe y exhaust gases from engines I0, lland I2 (the number of engines being arbitrary) are collected in a mainI3 by means of the connections thereto numbered Illa, Ila, l2a, saidmain being joined to a mixing chamber I5 by means of Vbranch I4. Alsoadmitted to chamber I5 through line I6 is a supply of oil, preferably invapor form, tobe cracked. To supply this, the oil is admitted preferablyto a heating coil Il passing by Way of pipe I8 to a flash chamber I9,the vapor from this being preferably superheated by being passed throughpipe 20, superheating coil 2| and finally to pipe I6. If superheated,the vapor may thereupon have a temperature of from 850 to 1000 degreesF. whereas. the hot gas Will have a temperature preferably in theneighborhood of 1100 degrees F., it being understood that thesetem-Yperatures may be varied considerably depending upon the initial crackingtemperature desired, and the amount of superheating of the vapors, ifany.` The initial cracking temperaturewill ordinarily be chosen around1000 degrees F. After mixing in the chamber I5, the intermingled gas andvapor passes through a connection 22into reaction chamber 23 Where thereaction is completed. The products leave'chamber 23 through pipe 24 andpass to fractionator 25the same consisting preferably of Ya combinedscrubber and rectier. Progressive dephlegmation takes place throughoutthe column from which the heaviest component or residue is led offthrough pipe 26, the same passing through heat exchanger 2l and admittedback into the column through pipe 28 at a point say a third of the Wayup. Also into pipe 23 may be admitted a fresh feed of oil to be treatedthrough pipe 29. A portion of the heaviest fraction is Withdrawn fromthe system through connection 29a. Somewhat above the bottom of thecolumn there is taken oif a fraction of intermediate boiling' pointYWhich mayY be termed a gas-oil fraction, the same passing Thosecomponents of the original stream of r through pipe 30 into vaporizer Ilto enter into theV cracked products consisting now chieiiy of the YusVready referred to. Pressure of the gas is therebyV increased from say 10pounds suction to 50 pounds discharge and the gas under such pressure isadmitted through pipe 49 intoabsorber 4I 5 wherein the light ends arewashed out of the gas by means of an oil of proper gravity admitted-tothe top of the absorber through pipe 42, which oil containing thedesired light fractions is removed through pipeV 43 whereupon it passesthrough said pipe to absorber still 45 heated by Vmeansof asource ofheat, not shown, preferably Y heat exchange, and in which the capturedvaporsV are released and pass out throughpipe 46-to a separator 41serving to separate the products into a rich gas passing out throughpipe 48 and a light distillate passing out through pipe 49. The Y leanoil from the absorber `still 45 is returned.

system such as to vaporizer I1 and superheater 2| where it is burned asfuel.

The rich gas leaving the separator 41 through pipe 48 passes preferablyinto a pipe 55 leading to gas storage tank 56 wherein it enriches thelean gas,a pump 48a being provided in said pipe 48. From the lean gasstorage 56 the gas is circulated to the engines III, II and I2 as bymeans of vpipes 65, reducing valve 65a, 66, 61 leading to V4tov engineI0; pipe 68 and branch pipes 69, 10 lead.-

ingto engines II and I2 respectively'.y Gas from asource'not shown maybe admitted to the system Vthrough pipe 15, compressed by compressor 16,a driven byrengine I I andY admitted to storage tank 45 11 whichconstitutes an auxiliary supply.` VGas leaves the tank 11 through pipe18 reducing valve .18a communicating withk pipe 1liV and also byk means`of pipe 19 with pipe 61 whereby in an Y emergency all three engines maybe run by gas 50 from tank 11. Such tank isV usefulffor example, inVstarting upthe systemV before a supply of cycle gas has `beenaccumulated in the tank 56.

It is .possible toV omit the compressor 31 and rely upon the backpressure ofthe internal combustion engines to `afford the necessarypressure in the system. The'greater the system pressure, however, theeasier is the recovery of the light endsv in the absorber 4I. In view ofthe fact that the engines are run 6o With'considerable back pressure, itis desirable to supply the gasy and, airjthereto under pressure.Desirably this excess pressure shouldbe about tWo Y pounds higherthanrthe back pressure so that Where the back pressure is 45 lbs. gauge,the gas and air feed to the engine should beisupercharged Vv gas leavingthe absorber 4I would have a fuel fThe lean gas leaves the absorber 4Ithrough the`V maybe heated by a coil heater 51a beyond the a value initself ample to run the internal combustion engines since it would runas a rule in the neighborhood of 300 to 400 B. t. u. per cubic foot. Therich gas from the condenser 41 on the other hand, has a very much higherfuel value, i. e., in the neighborhood of 1500 to 2000 B. t. u. percubic'foot so that a blend of the two gases may have a fuel value ashigh as from 860 to 1G00 B. t. u.s or approximately the equivalent ofnatural glas. n

It will be understood that various changes may be made Yinthearrangement ofv apparatus Without departing from the spirit of myinvention or the scope of the'appended claims.

. I claim:

phase which consists in burning fuel in an internal combustion engine toproduce exhaust gases Vhaving a temperature in excess of 950 F.,vaporizing the oil to be cracked, mingling the oil vapor so produced andsaid exhaust gases under condi'- tions bringing about cracking 0f SaidOil vap0r,' subjecting the mixture of products of the crackl c 15 f1.'The method of cracking oil in the vapor ing reaction which include vsaidmingled gases to i.

dephlegmation with recovery of a gasoline-like product, utilizing theenergy of said internal combustion engine to compress the uncondensedportion of said mixture of products in order to propel them throughthe'sy'stem and to facilitate,l condensation 'of the vapors remaininguncon,r densed, then passing said mixture so compressed to an absorberto strip therefrom said light vapors.

2. In the method of cracking oil in the vapor phase by the agency of ahot gas havinga tem-V perature in excess of 950 F., Which is mingledwith the vapor of the oil to be cracked, Vthe steps of subjecting themixture of products of thel exhaust gas from said engine as the cracking3. In'the method of cracking oil in the vapor phase bythe agency of ahot gas having a teme perature in excess'of 950 F.which is mingled Ywith the vapor of the oil to be cracked, the steps' of subjecting themixture of products .of the cracking reaction including the mingledv gasand combustible gas formed in they cracking reaction to dephlegmationwith recovery of a gasoline-like product, leaving a residual gasincludingY sai'dl combustible gas, passing said residual gas through anabsorber to separate out lean gas from the rich gas and bleeding atleast a portion of said lean gas from the system, burning the enf richedVgas soproduced in an internal combustion engine and deriving usefulmechanical Work therefrom and then utilizing the hot exhaust gasfrom'said engine as the cracking agent.

4. In the method of cracking oil in the vapor phase by the agency of ahot gas having a temperature in excess of 950 F.'Which is mingledWith'the vapor of the oil to be cracked, the steps of subjecting themixture of products of the cracking reaction including the mingled gasand combustible gas formed in the cracking reaction to dephlegmationwith recovery of a gasoline like product, leaving a residual gasincluding said combustible gas, passing said Vresidual` gas through anabsorber to separate out lean gas from the rich gas and bleeding atleast a portion of said lean gas from the system, burning the enrichedgas so produced in an internal combustion engine, utilizing the energyof said internal combustion engine to compress gaseous fuel and feedingsaid compressed gas to said internal combustion engine, and utilizingthe hot exhaust gasl from said engine as the cracking agent.

5. The method according to claim 2 in which 10 part of the residual gasis heated by heat derived from the reaction products and then added tothe gas constituting the cracking medium.

6. The method according to claim 2 in which part of said mechanicalenergy derived from the combustion of the residual gas is used tocompress thev stream of products passing through the system preferablyat the point just prior to vthe absorber.

